Area Forecast Discussion
Issued by NWS Upton, NY

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000 FXUS61 KOKX 230623 AFDOKX Area Forecast Discussion National Weather Service New York NY 223 AM EDT Fri Jun 23 2017 .SYNOPSIS... A warm front approaches tonight and passes Friday. A cold front moves across Saturday and behind it another cold front will slowly approach from the north. The second cold front moves in and weakens early next week. This eventually moves farther northeast of the region toward the middle of next week with a strong high pressure area building in from the west thereafter. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... Minor updates to reflect current trends. Decoupling has occurred with the loss of solar insolation, allowing earlier gusts to diminish across the NYC metro area. Previous discussion remains valid. Warm and increasingly humid conditions will prevail tonight. Will need to keep an eye on any stratus and fog development, possibly advecting northward from the ocean later tonight. Long Island and southern CT most likely locales. Otherwise, weak shortwaves/vorts in W/SW upper flow, along with an approaching warm front could trigger a few showers/possible thunderstorms overnight. With clouds and southerly flow, warm temps overnight expected with not much disparity across the region. A mos/model blend followed. There is a moderate risk for the development of rip currents at the eastern Suffolk ocean beaches into this evening. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SATURDAY/... A series of weak upper level shortwaves/vorts could trigger a few showers/thunderstorms Friday as a sfc warm front passes in the morning. Capes build, with highest values where they typically are, across the interior away from marine layer. As layer precipitable water values climb to over 2 inches, will mention heavy rainfall with any thunderstorms. Instability wanes somewhat Friday night, but thunder remains a possibility and heavy rain is certainly possible in any convection. In general, expect scattered to numerous coverage, but it will not rain all the time. Warm temps in the 80s during the day can be expected, and 60s to 70 at night, along with high humidity. Again, not much disparity in low temps is expected due to clouds, southerly winds and high humidity in place. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... Overall, looking at the large scale, a trough remains in the Northeast this weekend into next week with a pattern change towards more ridging evident towards the end of next week. The area will have the jet stream in the vicinity of the region through early next week. It will be oriented from SW to NE with a max speed of roughly 100-120 kt. At the surface, a cold front will be approaching the region Saturday and moving across from NW to SE through the day. A weak low develops along the front with a sharp mid level shortwave aloft. The front moves farther offshore SE of Long Island Saturday night. A weak pressure pattern sets in place thereafter for Sunday and Sunday night. A cold front approaches and weakens as it moves in early next week. Eventually, building high pressure well west of the region starts to build in mid to late next week. In terms of weather, a wet start to the weekend with showers and a few thunderstorms Saturday. Instability is lower Saturday so left thunderstorm coverage as isolated. Showers are likely. Weather becomes drier from NW to SE during the afternoon with more westerly flow getting established. Mainly dry conditions are expected thereafter. There will be mainly diurnally driven low chances for showers and thunderstorms Sunday through early next week, but expect majority of the region to remain dry. Temperatures a little above normal Saturday but otherwise right near normal values for the rest of the long term period. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... A warm front approaches the region overnight, and lifts nwd thru the area Friday. Mainly VFR overnight, however there is a chance that some areas of IFR develop for a few hours, especially east for KGON AND KISP. Pockets of MVFR are possible again on Fri with cigs around 2500 ft. There is also some potential for eastern terminals to briefly go to MVFR in the late afternoon due to low stratus. For now the tafs indicate VFR because coverage is in question and too uncertain at this time. More widespread sub VFR conditions are expected late in the TAF period after 0z Saturday (see outlook below). There will be a chance of isold-sct shwrs thru the day (Friday), with the best potential for thunderstorms aft 20Z, particularly in areas along and w of the Hudson River. Sea breeze flow will lessen overnight, and veer to the sw as the flow weakens. The sea breeze may attempt to back winds closer to the s again aft 16Z Fri. .OUTLOOK FOR 00Z SATURDAY THROUGH TUESDAY... .Friday Night...MVFR or lower in shra/tsra. IFR or lower conditions possible in stratus/fog for eastern terminals for the first half of Friday Night. .Saturday...MVFR or lower possible in shra/tsra. S/SW winds. .Saturday night-Sunday Night...VFR. NW winds...becoming W/SW. .Monday...VFR. Slight chance of afternoon shra/tsra. SW winds. .Tuesday...VFR. Chance of afternoon shra/tsra. SW winds. && .MARINE... Southerly winds tonight remain well below SCA criteria, but do expect these southerly winds to increase by Friday afternoon and into the evening. At this time, will issue a SCA for the ocean waters for winds 20 to 25 kt, and building seas in the 5 to 6 foot range. The remainder of the waters should remain below SCA criteria. The other hazards for mariners will be showers/thunderstorms, and reduced visibilities in fog. In terms of winds, the pressure gradient will be weak enough through the long term marine forecast period (Saturday through Tuesday) to keep winds below SCA criteria. However, the seas on the ocean will probably still have southerly swell contributing to higher seas of 5- 6 feet on the ocean that are forecast to last through early Sunday. The 5-6 foot seas will last through the day Sunday for the ocean east of Fire Island inlet. Seas are forecast to go below 5 feet for all ocean waters Sunday night through Tuesday. Non-ocean waters stay below 5 feet the entire long term marine forecast period. && .HYDROLOGY... There is the potential for heavy rain late Friday into Sat as the remnants of Cindy move through. At this time expect at least flood advisories to be issued. It is too early to tell if flash flooding will occur due to the lack of instability. This potential could be added to the HWO in subsequent forecasts. Otherwise, no other hydrologic concerns. && .TIDES/COASTAL FLOODING... Astronomical tides are running very high, especially during the evening high tide cycles through Saturday. Less than 1 ft of surge is needed during these evening high tide cycles for minor flooding, and in some cases less then 1/2 ft. The expected S/SW flow is not favorable for surge, but a background anomaly will likely be enough for minor coastal flooding of the most vulnerable coastal locales along the south shore bays of Western Long Island, along Jamaica Bay, and along western Long Island Sound during this time. && .EQUIPMENT... KOKX weather radar is scheduled for maintenance starting Friday June 23rd for a period of 3 days. && .OKX WATCHES/WARNINGS/ADVISORIES... CT...None. NY...None. NJ...None. MARINE...Small Craft Advisory from noon today to 6 AM EDT Saturday for ANZ350-353-355. && $$ SYNOPSIS...JM/PW NEAR TERM...MD/PW SHORT TERM...PW LONG TERM...JM AVIATION...JMC/JE MARINE...JM/PW HYDROLOGY...JM/PW TIDES/COASTAL FLOODING... EQUIPMENT...

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